MESENCHYMAL CELLS 



but many lymphocytes near the centre of the follicles 

 showed a Hght fluorescence. They considered that these 

 cells might also be producing antibody in smaller amounts. 



Ortega and Mellors (1957), using human material and 

 examining, not for specific antibody but for production of 

 gamma globulin, lay much stress on what they call intrinsic 

 cells present in the germinal centres. These produce what 

 appear to be symplastic aggregations, the cytoplasm showing 

 fluorescence characteristic of gamma globulin. These 

 probably correspond to the cells found by Coons in his 

 experimental animals. 



An objective survey of the facts could well lead to the con- 

 clusion that there was no evidence of immunological activity 

 in the small lymphocytes which make up the dominant 

 majority of lymphoid cell populations. All the positive results 

 could well be ascribed to plasma cells, large lymphocytes and 

 intermediate forms. The position might, however, take an 

 entirely different aspect if small lymphocytes can be con- 

 verted into other functional forms. At this stage, therefore, 

 it is highly desirable to consider the transformations of the 

 mesenchymal cells. 



2. Interrelations of mesenchymal cells 



There does not yet seem to be an adequate technical method 

 for determining the intermediate stages that must have been 

 interposed between the undifferentiated mesenchymal cell 

 of early embryonic life and any given cell observed, for 

 example, in a lymph node where antibody production is in 

 progress. Any presumptive genealogy is likely to have many 

 weak links but the only practical approach is to adopt with 

 appropriate minor reservations the views most widely held 

 in common by histologists of repute. Taking Maximow and 

 Bloom (1948) as the most widely used text on mammahan 

 histology for a starting point, we can in the first instance omit 

 the granulocyte series although the ubiquitous association of 

 eosinophils with immune responses will call for subsequent 



no 



